Ore flotation method



United States Patent Office 3,421,621 Patented Jan. 14, 1969 4 Claims ABSTRACT OF THE DISCLOSURE A method for the concentration of minerals in flotation cells where preconditioning of the mineral feed with a flotation reagent is not required. More particularly, the method of forming an intimate mixture of flotation reagent, water and air at a point in the cell below that of the addition of the mineral feed to be floated and then contacting the feed with this intimate mixture.

Background of the invention This application is a continuation-in-part of application Ser. No. 466,546, filed June 24, 1965 and now Patent No. 3,371,779. That application discloses and claims a concentration method and a flotation cell wherein a constriction plate is placed across the lower portion of the flotation cell and used to uniformly distribute aerated water formed therebelow into the flotation chamber to float a mineral feed.

In such flotation the flotation reagent has customarily been admixed with the mineral feed prior to addition to the flotation cell or introduced directly into the flotation cell together with the ore feed. Such methods have not proven entirely satisfactory since the slime present in the feed tends to consume the flotation reagent, resulting in a poor concentration or the need for larger amount of reagent. Attempts to overcome the adverse effects of slime as by addition of the flotation reagent below the point at which the ore feed is added to the flotation cell as described in Patent No. 2,758,714 have not proven entirely satisfactory, since a localization of flotation reagent occurs. This results in too little reagent at some portions of the flotation cell and in too great a concentration in others. The result in both cases is ineffective flotation.

Summary of the invention It has been found that improved flotation and the use of reduced levels of flotation reagent can be accomplished by first forming an intimate mixture of flotation reagent, water and air.

Briefly stated, the present invention comprises the method of ore flotation by forming an intimate admixture of flotation reagent, water, and air, and then treating the ore feed with such intimate admixture. In a preferred embodiment the process comprises introducing the ore to be floated into a flotation cell having a relatively quiescent flotation compartment, introducing air, water and flotation reagent into a hydraulic compartment disposed below the flotation compartment, producing an intimate dispersion of these materials, and uniformly distributing the intimate admixture from the hydraulic compartment into the flotation compartment where the ore is to be treated.

Detailed description The flotation cells to be used in the present method do not form any part of the invention and any of those known to the art can be used. Preferred, however, are the flotation cells in which the flotation ore and water are added to the cells at the bottom thereof. The most suitable cells of this type are those set forth in Patent No. 3,371,779. These latter cells are preferred because the intimate admixture of air, water, and flotation reagent can take place below the constriction plate and the admixture then uniformly distributed through the cell insuring the most effective flotation.

As to minerals that can be concentrated, any can be used wherein no pre-conditioning between the ore and the flotation reagent is required. Thus, for example, the instant invention is not suitable for the anionic flotation of phosphate but is suitable for the cationic flotation of phosphate using amines. The invention is equally suitable for the flotation of such ores as coal, copper, zinc, lead, iron, and the like.

As to the flotation reagents any of those presently used for the flotation of the minerals noted above can be used. Thus, for cationic flotation of phosphate any of the usual fatty acid amines can be used either with or without kerosene. For copper ore and coal flotation, methyl isobutylcarbinol can be used, although for coal flotation, a light oil, such as diesel oil or kerosene, is preferably combined with the methyl isobutylcarbinol. In the same manner the methanol, other alcohols, Xanthates, and the like known reagents can be used for flotation of the mineral ores; the specific reagent used being dependent upon the ore to be treated.

The instant invention is particularly suitable for the cationic flotation of phosphate ore where the silica is removed from the phosphate. The usual cationic flotation reagent is admixed with the air and water in the bottom of the cell resulting in a substantially homogeneous air, water, and flotation reagent mixture in which the reagent is uniformly dispersed and the air is in the form of fine air bubbles; it being known that the finer the bubble size the more efficient the flotation. Such intimate admixture can be accomplished by adding the flotation reagent to the water in the aspirator shown in Patent No. 3,371,779. Admixture can also be obtained by providing a separate mechanical mixer at the bottom of a cell, preferably utilizing the apparatus of Patent No. 3,371,779 and placing the mixer below the constriction plate.

The proportion of flotation reagent used is dependent upon the particular type of flotation reagent used, the amount of slime, and physical characteristics of the particular ore to be concentrated. This can be readily determined for each particular set of conditions by running a sample test. With phosphate ores of varying slime content using a fatty acid amine reagent, for example, from about 0.1 pound to about 1 pound of the reagent can be used for each long ton of phosphate ore.

In the examples that follow and elsewhere herein, proportions are expressed as parts by weight unless specifically stated to the contrary.

EXAMPLE 1 Cationic phosphate flotations were run in the same apparatus (a single flotation cell as set forth in Patent No. 3,371,779) utilizing the same reagent (35 parts fatty acid reacted with diethylene triamine-65 parts kerosene), same feed rate, and same phosphate feed. In one run the reagent was injected into the top of the cell with the feed, in the conventional manner, and in the second run the reagent was injected into the cell through the aerator below the constriction plate after being thoroughly admixed with the air and water. The results were as follows:

TABLE I Point of Feed one. Tails R atio injection BPL BPL cone. Recovery of reagent BPL Insol Bottom.-- 34. 5 60. 0 24. 8 3. 29 l. 81 96 Top 34. 5 53. 2 32. 6 3. 40 1. 60 96 The injection of the fatty acid amine kerosene reagent through the aerator into the bottom resulted in a 60 BPL concentrate as opposed to a 53 BPL, both with similar recovery. Visual examination indicated that a finer, more abundant, and uniform bubble structure was obtained with the admixture of the reagent with the air and water.

EXAMPLE 2 EXAMPLE 3 A series of flotation concentration runs is made utilizing the flotation apparatus of Example 1 with coal, zinc, lead, and iron ores. For each ore addition of the suitable flotation is varied by being added to the top of the cell with the feed and into the cell through the contriction plate after being admixed with the air and water. In each instance bottom addition results in a higher ore concentrate.

It will be understood that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope of the invention.

What is claimed is:

1. Process for concentration of minerals requiring no pre-conditioning with a flotation reagent by froth flotation of an aqueous pulp containing mineral particles which comprises introducing the mineral containing pulp into a flotation compartment containing a relatively quiescent body of said aqueous pulp,

forming an intimate admixture of a flotation reagent for said mineral to be concentrated, water, and air in a hydraulic compartment disposed below and in fluid communication with the lower portion of the flotation compartment,

uniformly distributing the admixture from the hydraulic compartment into the lower portion of the flotation compartment,

maintaining the static pressure of the admixture in the hydraulic compartment sufliciently above the static pressure of the mineral-containing pulp in the lower portion of the flotation compartment to prevent the flow of pulp from the flotation compartment into the hydraulic compartment,

withdrawing an overflow float fraction containing floated particles of pulp from the top of the body of aqueous pulp in the flotation compartment, and

withdrawing an underflow fraction containing nonfloated particles of the pulp from the lower portion of the flotation compartment.

2. The process according to claim 1 in which the difference in pressure between the aerated water in the hydraulic compartment and the aqueous pulp in the flotation compartment is at least 0.5 p.s.i.

3. The process according to claim 1, wherein the mineral particles are phosphate and the flotation reagent is one suitable for the cationic flotation of phosphate.

4. The process according to claim 1, wherein the mineral particles are coal and the flotation reagent is a combination of methyl isobutylcarbinol and kerosene.

References Cited UNITED STATES PATENTS 1,167,835 1/1916 Norris 209-170 2,753,045 7/ 1956 Hollingsworth 209-470 2,783,884 3/1957 'Schaub 209- 3,298,519 1/1967 Hollingsworth 209-166 X 3,343,674 9/1967 Zandon et a1 2.09166 HARRY B. THORNTON, Primary Examiner.

TIM R. MILES, Assistant Examiner. 

